There has been known a technique of clustering multiple storage devices such that even when one of the clustered storage devices stops due to a failure or the like, another storage device having been in a standby state may be used to continue operation.
For example, for a storage system operated with two storage devices clustered, there has been an approach in which: data in storage areas as access targets from a host device is copied to storage areas of the storage device in a standby state to synchronize the respective storage areas; and then if the storage device in an operation state stops, the host device is allowed to continue task processing by changing the access targets of the host device to the storage areas of the other storage device.
Furthermore, there has been known a technique of not only copying data in a storage area of one storage device into a storage area of a first different storage device but also further copying the data of the storage area at a copy location in the first different storage device to a storage area of a second different storage device located in a remote place.
FIG. 20 is a diagram illustrating a configuration of a conventional storage system.
A conventional storage system 500 illustrated in FIG. 20 includes a first storage device 501, a second storage device 502, and a remote storage device 503.
The first storage device 501 and the second storage device 502 are clustered. A storage area 501a of the first storage device 501 is synchronized with a storage area 502a of the second storage device 502, and data in the storage area 501a of the first storage device 501 is copied (synchronously copied) to the storage area 502a of the second storage device 502.
For example, when a host device, which is not illustrated, performs writing to the storage area 501a of the first storage device 501, copying is performed to synchronize the storage area 501a of the first storage device 501 to the storage area 502a of the second storage device 502.
In addition, data in the storage area 501a of the first storage device 501 is asynchronously copied to a storage area 503a of the remote storage device 503. For example, if writing is performed on the storage area 501a of the first storage device 501, the data in the storage area 501a of the first storage device 501 is copied to the storage area 503a of the remote storage device 503, at a timing when there is no access to both the first storage device 501 and the remote storage device 503.
The related art has been disclosed in Japanese Laid-open Patent Publication Nos. 2007-264946 and 2005-182222, for example.